Monolithic multiaperture core device



QMONOLIJ'I'HIC MuLTiAPERTu'RE CORE DEVICE Filed Dc. 13, 1966 2 shets sheet z United States Patent US. Cl. 340-174 11 Claims ABSTRACT OF THE DISCLOSURE A magnetic core structure wherein separate circuit wmdmgs are coupled to the core through a series of small holes insulated each from the other only by the core material.

This invention relates to magnetic core structures of the type utilized in memory and logic devices and to methods for making such structures.

A considerable efifort has been made to utilize the storage and logic capabilities of square loop magnetic material and much of the electronic data processing apparatus in use today is made up of core structures in the form of toroids, sheets, strips and other core structures made of such material. The advantages of intelligence storage without continuous drive power through a device which has an infinite life have no doubt sponsored this. One of the main limitations on core use has been the diificulty encountered in wiring; applying necessary input, output and drive windings. Drive power requirements and to a certain extent frequency response and overall elliciency is related to the amount of magnetic material employed to define a given core and generally speaking, the smaller the core the better. This smallness has aggravated the wiring problem which is directly related to physical size. Even so, the largest usage of magnetic cores has been in memory planes made up of small toroids. It is thought that this usage is due to the fact that memory plane circuits generally require only a single winding turn through a core body for input, output and drive signals. The much lesser usage in the larger multiaperture magnetic cores employed for logic purposes and for providing relatively complex circuit functions is believed to be due to the fact that these cores have circuits which include a number of turns through the core apertures; making production uneconomical. To illustrate the foregoing a comparison may be made between a typical toroid memory device as is shown in Patent 3,012,231 and a typical multiaperture logic device, as is shown in Patent 2,810,901.

Even with single turn circuits there has been a problem with winding installation. That the problem is one which has existed for some time is demonstrated in a number of patents: including patent 2,911,627 which provides cores slotted to receive windings and then faced over with magnetic material to close the air gap of the slot; Patent 2,910,675 which shows cores having conductive pins fitted therethrough and terminated to printed circuits for the purpose of adaptation of core devices to automatic production; Patent 3,127,590 which features a core geometry to facilitate straight through windings; and Patent 3,129,494 which shows a method for automatically winding cores including multiaperture cores with a plurality of turns. Still other patents of interest to show the problem and an attempt at a solution are Patent 3,085,899 which discloses the concept of molding up cores and windings in laminations with core material and conductive material being placed between different steps of firing; Patent 2,882,519 which deals with obtaining desired winding patterns on plate type structures;

3,506,973 Patented Apr. 14, 1970 and Patent 3,184,719 which deals with cores made through molded and printed circuit techniques.

Some of the foregoing approaches are simple, but many of them are complex. None of them, however, solve the problem of providing multiple turns in a magnetic core structure without the need for insertion of separate conductors through the same aperture. None of them deal with the problem of placing turns having different functions in a multiaperture core structure without having to insulate between turns. In general, none of the prior art teaches how to obtain a wired multiaperture core structure capable of complex functions in a device which can be readily mass produced.

It is an object of the invention to provide a means and method for obtaining multiple winding turns through a core structure wherein winding placement and insulation between turns having multiple turns therethrough is inherently accommodated.

It is a further object of the invention to provide a simple and inexpensive method and means for achieving multiple turn windings in magnetic core structures for input, output or drive purposes.

It is still a further object to provide a wired multiap/erture core device whereon windings may be formed through plating procedures.

It is still another object of the invention to provide a core structure for memory and logic applications which can be more easily produced and which assures the proper placement of windings by permitting an automated installation of windings on a core structure.

It is yet another object to provide a core structure and circuit which is more reliable than devices heretofore available.

The foregoing problems are overcome and the foregoing objectives are attained by the invention through a magnetic core structure wherein separate circuit windings turns are placed on a given core through a series of small holes insulated each from the other only by core material with a spacing which makes the various winding turns link the same flux paths for certain purposes and different flux paths for other purposes. Thus, when a given core geometry and drive circuit calls for several turns which would be normally threaded through a single common aperture to achieve agiven function, the invention contemplates a core structure having separate small holes fitted with conductive pins or plated through to be connected externally in a fashion to provide the desired turns. In one aspect the invention contemplates molding and firing a body of magnetic material with extremely small holes therein grouped in a pattern sufficiently close together so as to simulate a much larger aperture wound with multiple turns. In this version the holes may be filled with solid conductive pins inserted therethrough or by standard plating techniques which deposit conductive material through such holes. Suitable linking conductive material to complete the windings may be deposited directly on the core material by plating techniques. Connector means joined in any suitable fashion to the individual conductive paths may be utilized to complete a connection to and from the circuit to provide the desired input, output or transfer functions. In another aspect of the invention it is contemplated that conductive wires or pins may be placed in holes in a pressed or molded core structure toremain therein as the core is fired; such pins then being interconnected in a suitable fashion thereafter to provide desired winding turns for use in a circuit.

In the drawings:

FIGURE 1 is a schematic view of a core wound in accordance with an accepted wiring scheme for input, transfer and output from a core device (enlarged approximately five times actual size);

FIGURE 2 is a plan view of a core having the same "unction as that shown in FIGURE 1, but made in accordtnce with the invention in one aspect thereof;

FIGURE 3 is a perspective of the core of FIGURE 2;

FIGURE 4 is a section taken along lines 4-4 of FIG- JRE 3;

FIGURE 5 is a plan view of a corner of the core of ?IGURES 2-4 (enlarged even further) showing the deails of the positions for turn placement;

FIGURES 6-8 are perspectives of a corner of the :ore of FIGURES 2-5 showing various turns and an tssociated flux distribution to explain the invention;

FIGURES 9 and 10 are plan views showing another :ore structure having windings and turns plated thereon 0 provide a completed two bit register; and

FIGURE 11 is a section through lines 11-11 of FIG- JRE 10.

Turning now to FIGURE 1, there is shown a core :tructure which has been used in a number of commerzial applications. The structure is wound in what is now t standard manner in accordance with a circuit which is )elieved to offer perhaps the best range of operation :or multiaperture devices. This type of circuit is termed VIAD-R' for Multi-Aperture Device-Resistance, and is lisclosed in detail in U.S. Patent No. 3,125,747 to D. R. 3ennion, granted Mar. 17, 1964, and in U.S. Patent No. 2,995,731 to J. P. Sweeney, granted Aug. 8. 1961. The :xact core structure and circuit is described in detail in U.S. application S.N. 305,780, now Patent No. 3,341,832 .n the name of Nitzan et al.

Cross of the type used in such circuits are typically nade of a square loop ferrite material which is first aressed into the desired geometry and then. fired at rela- ;ively high temperature. Most of the materials have in- ;ulating qualities. Prior to firing it is a standard practice :0 utilize a binder which is burned out during firing to leave the ferrite material having square loop characteristics. Considerable shrinkage (twenty or thirty percent) Jccurs during firing and cooling of the formed core genmetry. The significance of these factors will be made apparent hereinafter.

The core shown as 10 includes a pair of major apertures 12 and 14, each placed in the body of magnetic material to define separate bit positions. In each half surrounding a major aperture there is a minor aperture such as [6, shown in the left half, which may be employed as an input aperture. Also in the left half is a slightly larger minor aperture shown as 18, which may be used as an output aperture. The minor apertures and 22 in the right half of the core structure 10 have similar functions. The minor apertures of the core define legs of maguetic material which permit multiaperture magnetic core operation including diodeless transfer and nondestructive readout, generally, and MAD-R operation, specifically. The core 10 is shown wound by windings including a coupling loop 24 linking the left core half to the right core half to transfer information stored in the left core half to the right core half. The coupling loop 24 is made to link the transmitter aperture 18 by two turns and the aperture 20 by one turn. This difference in turns is to achieve a sufiicient gain to overcome the losses inherent in the device. Further included in an input winding 26 linking the input aperture 16 and an output winding linking the transmitter aperture 22. The input Winding 26 has one turn and the output winding 28 again has two turns for the reasons mentioned. Also threading the core are drive windings including an advance winding 30 which is made to link the major aperture of the left hand portion of the core by several turns and an advance winding 31 made to link the major aperture 12 by several turns. The clearing windings serve to cause an advance of intelligence stored in the core and are pulsed at separate times in an advance cycle. A further drive winding 32 is provided to prime the core through one turn made to link both transmitter apertures 18 and 22 and operable to prime the material about such apertures prior to transfer initiated by the advance pulse of the transfer cycle.

In an actual core like 10 the apertures 18 and 22 have diameters which were approximately .0 30 of an inch. In order to provide windings it is necessary to insert insulated wires on the order of a few mils in diameter through these apertrues. Where there is more than a single turn around the legs as in loop 24 it is necessary to carry the wire back through the apertures again in the manner indicated in FIGURE 1. Aside from the difficulty of inserting small wires through small apertures, other problems are encountered including the possibility of scraping insulation oif of the wires by engagement with the hard and abrasive ferrite material employed for codes. As will be appreciated by those skilled in the art, the wiring procedure for devices like that shown in FIGURE 1 is almost altogether manual and, notwithstanding a considerable skill developed to do this task, variations in skill and approach from worker to worker tend to result in undesirable variations in windings from core to core.

Techniques which might permit an automated manufacture such as plating of conductive paths or jig mounting of conductors have proven to be extremely difiicult with core structures like that of 10, which is representative of a typical core winding scheme. Those skilled in the art will appreciate that many applications call for considerably more turns placed through an aperture than those shown.

Turning now to FIGURE 2. there is shown a core 40 having the same overall function as the core 10 shown in FIGURE 1. The core 40 includes major apertures 42 and 44 and the leg widths of the various legs of magnetic material are substantially the same or the equivalent to those in core 10 in FIGURE 1. In lieu of simple minor apertures having multiple apertures at input, output and drive positions in these legs, the invention contemplates a series of turn positions placed in a closely spaced pattern to simulate multiple turns through a single aperture with the material itself serving to insulate between turns. These positions are labeled A, B, C and D, for the left half of the core, the right half having a similar array. The positions A, B, C or D may be defined by either holes or by conductive material, wires or pins. In accordance with one embodiment of the invention and contemplated thereby, a core like 40 may be molded, cast or pressed out of suitably prepared magnetic material to have the small holes therein in the pattern shown. The holes are made just large enough to accommodate a conductive pin or wire which is placed therein with the core then being fired with the wires in place. If this procedure is followed the wire utilized is, of course, uninsulated and must be of a material to withstand and the considerable firing temperatures employed. With ferrite material systems having firing temperatures up to 2600 F. conductors such as platinum are recommended. It has been found that molding or casting is preferable when the holes are as small as is contemplated by the embodiments herein described, although pressing is fully contemplated.

Alternatively, and as another embodiment, the cores may be molded, cast or pressed in the geometry shown with small holes therein; the core fired and then, after firing, conductive material placed in the holes in the form of either precut pieces of uninsulated wire or plating material deposited therein.

As far as the invention is concerned the choice of one of the above procedures will depend to an extent upon the particular material used, the amount of usage contemplated for a given core geometry, and overall, the extent to which expected production will permit savings to be made. It is fully contemplated by the invention that the techniques may also be used to advantage with materials which do not require firing to the temperatures of the magnesium, copper or cobalt ferrite systems presently in use.

FIGURE 3 shows the core of FIGURE 2 with conduc tive Wire or pin members P located at the input and output positions in the core. FIGURE 4 shows the core of FIG- URE 3 in section with certain of the members P shown therein. In FIGURE 5 a corner of the core 40 is shown enlarged with A, B and C, as positioned in a leg of the core. As a basic aspect of the invention A, B and C are positioned relative to each other with a certain spacing relative to the amount of material which will be linked when the conductive members P are joined to windings. Consider first the prime winding shown in FIGURE 1 as lead 32 linking aperture 18 to prime flux set in the inner leg around into the outer leg of material surrounding 18. Referring to FIGURE 6, a portion of the core is shown with the position A emphasized and the positions B and C, for the moment, de-emphasized and with flux set in the core as it would be when the left hand of the core contains a binary 1 or is in a set state. If a current is applied to P in the polarity shown in FIGURE 7 an MMF will result which will switch the flux in the material about the pin, not under the coupling loop turns, into an orientation as indicated in FIGURE 7. This is known as priming and the core half is driven into a primed set state preparatory to a transfer of the state stored in the core. As can be appreciated from FIGURE 5, the amount of flux which can be transferred via the coupling loop is dependent upon the amount of flux set into the outer leg when the core is primed. The placement of position A with respect to the cross-section through the core material determines this amount of flux and, with the invention, the amount of flux which can be switched can be easily controlled.

In FIGURE 5 there is shown a third cross-sectional area AWIII between A and a tangent touching both B and C. Generally, this area should be made as small as possible. For best efficiency on transfer of a binary 1 the areas should be made so that AWI is equal to or greater than AWII-l-AWIII. For minimum binary zero output the areas should be made so that AWI+AWIIAWIII is equal to or less than the area represented by W.

FIGURE 8 shows a portion of the corner of the core with conductive member P placed through the positions B and C and with leads attached thereto for the purposes of illustration to form a coupling loop linking the outer leg of core material by two turns equivalent to the windings shown in FIGURE 1 or loop 24. The loop load is as represented. Current caused to flow in a coupling loop is dependent upon the voltage induced in these turns by flux switched thereunder. This flux is controlled by the amount of material in the cross-sectional areas BW or CW, shown in FIGURE 5; the lesser area controlling if the areas are different. The total current caused to flow in the coupling loop is then the net current resulting from voltage induced in the windings responsive to flux switched through cross-sectional areas in BW and CW. It may be desirable to place points B and C relative to the core geometry to define a net cross-sectional area of material in which the flux switched is approximately equal to that switched in AWI so that the amount of flux switched during transfer under clear drive is substantially the same as the amount of flux primed under the coupling loops by the priming MMF applied to the conductor through position A. Again, the invention technique permits a variation in the amount of flux switched under the coupling loops by varying the positions B and C relative to the position A.

As can be appreciated, and as an important aspect of the invention, the winding diificulties which accompany the prior art approach, as indicated in FIGURE 1, are reduced. Even in applications wherein it is desirable to place fixed pins through small apertures it has been found to be easier relative to the prior art to place fixed length, fixed size pins through fixed size apertures and then to connect such pins through printed circuits, soldering the tabs or the like; easier from both a production control standpoint and labor involved. More importantly, the devices which result from the invention technique have a more consistent performance and, therefore, the overall reliability of a system is improved.

FIGURES 9, 10 and 11 relate to another embodiment of the invention, including a larger two bit position core structure having windings plated thereon to form a circuit like that of FIGURE 1. The core shown as 50 includes four major apertures 52, 54, 56 and 58, defining four major paths of flux closure labeled 0 E 0 E to represent odd and even bit positions. At the four outside corners are positions A, B, C for prime and coupling loop turns. The position D is for an input to the core and, particularly, to the bit position 0 A further position E is provided for a coupling loop input from a bit position such as 0 to a bit position such as E The center aperture 59 is provided to eliminate uonsaturable material.

In accordance with the invention, the core 50 is molded with small holes at A, B, C, D and E. The core is then fired, cooled and the entire core is plated with plating material being deposited through the holes at A, B, C, D and E. Next, through standard photo-etch procedures, the windings shown in FIGURE 7 are formed on the core structure. These windings include a prime winding 60 which extends through each position A to prime each bit position. The polarity shown indicates the desired circuit for serial transfer from O to E E to O O to E and out of the core. The coupling loops are formed as at 62, linking O to E at 64, linking E to O and at 66, linking O to E The linking conductive paths forming these windings are positioned so as not to contact each other, but to join with the positions A, B, C and D to complete the circuit.

Next, the entire assembly is insulated by a standard coating process and a second winding pattern forming the advance turns is deposited as shown in FIGURE 8. FIGURE 9 shows the insulation as 80. Winding 70 represents advance 0 drive and 72 represents the advance E drive. With suitable input and output connection made to the positions for advance and prime drive and for intelligence input and output, the structure may then be used as a two bit shift register.

It is contemplated that a variety of circuit devices having any of the additional standard functions such as logic or nondestructive readout may be made utilizing the invention technique.

In a core like 50 for shift register use the dimension in inches were as follows:

W: 0.063 AWI: 0.044 AWII=0.028 AWIII: 0.012

Having now disclosed and described the invention in terms intended to enable its practice in a preferred mode, We define it through the appended claims.

What is claimed is:

1. In a multiaperture magnetic core device of the type utilized to store and/or manipulate intelligence in the form of defined states of magnetization, a core body of insulating magnetic material having a major aperture with legs of magnetic material therearound defining a major flux path, circuit means linking said major flux path to apply setting and clearing drive MMF to switch flux therein, and output means linking said core to provide an output therefrom, said output means including a plurality of turns piercing a leg of said core at a substantially common position to define a minor flux path having a portion in common with said major flux path, said turns being formed of individual windings placed through individual paths through said leg insulated each from the other by the material of said core and being connected in a circuit to develop an output signal responsive to flux switched under the turns formed thereby responsive to clearing of said core.

2. The device of claim 1 wherein proximate the posiion in said legs wherein said turns are located there is )rovided at least a further turn piercing said core and )perable responsive to current drive to develop an MMF twitching flux in a minor flux path linked by first said nentioned turns to prime said core.

3. The device of claim 1 wherein the said core body ncludes at least another major aperture with legs of nagnetic material therearound defining a major flux ath and said turns are linked to a coupling loop which 5 linked to said second major flux path and operable to vransfer magnetization states from the first mentioned lux path to the second flux path.

4. The device of claim 3 wherein the coupling loop .ncludes lesser turns linking the second flux path to pro- Jide a gain in signal transfer from the first mentioned najor path relative to signals developed in said coupling .oop when flux is switched in said second flux path.

5. The device of claim 3 wherein the said coupling .oop includes a lesser number of turns piercing a leg of :he second major aperture at a point to link the material thereof to switch flux about said major path.

6. In a magnetic core device of the type utilized to store and/or manipulate intelligence, a core of square loop material having insulating qualities, a major aperture defining a major path of flux closure surrounded at least in part by legs of material, a circuit linking said :ore to switch flux therein to establish states of magnetization representative of intelligence including a state wherein substantially half the flux is oriented in one direction and substantially half in an opposite direction relative to inner and outer portions of the major path, to respond to flux switched therein and means including said :ircuit to produce an output signal, said means being comprised of turns separately piercing the core at a substantially common location and insulated from each other by said core material to define a minor path of flux closure having a leg in common with the inner portion of the major path and operable in response to flux switched in the outer portion of the major path to produce said output signal.

7. The device of claim 6 wherein a separate turn connected to said circuit is made to separately pierce said core at said common position to prime flux set into said inner portion into said outer portion by switching flux locally in said minor path.

8. In a multiaperture magnetic core structure of the type utilized to store and/or manipulate intelligence in the form of states of magnetization, a core body of insulating magnetic material including at least one major aperture defining a major flux path through legs of mate rial surrounding a substantial portion of said major aperture, a circuit including input and drive windings linking said core to provide a setting and clearing MMF to switch flux therein and further including a plurality of turns linking said core to provide an output therefrom, said turns being formed by a plurality of minor apertures grouped in a cluster, said turns linking substantially the same minor flux path with individual turns fitted through individual apertures.

9. The device of claim 8 wherein said individual turns are substantially supported along the length thereof by the magnetic material of said core.

10. The device of claim 8 wherein said turns are comprised of deposited conductive material plated through said minor apertures.

11. In a magnetic core device having an end used to store and/ or manipulate intelligence in the form of states of magnetization, a core body of insulating magnetic material including a major aperture defining a major path of fiux closure, substantial portions of which reside in legs extending about at least portions of said major aperture, the magnetic material of said core being in a condition prior to at least the final step of firing, conductive paths piercing said core at substantially a common position in said legs, said conductive paths being surrounded by a substantially common minor path of flux closure and being separated each from the other by a small amount of magnetic material whereby to define turns linking said core.

References Cited UNITED STATES PATENTS 7/1961 Brown 340174 3/1968 Wyrick 340-174 US. Cl. X.R. 29-604 

